Musnad Ahmad 32:413

'Abd al-Rahman ibn Mahdi narrated to us, from Aban—meaning Ibn Khalid—Ubayd Allah ibn Rawahah narrated to me, he said: I heard Anas ibn Malik [say] that he did not see the Messenger of Allah, peace and blessings of Allah be upon him, pray the Duha prayer, except when he would go out on a journey or arrive from a journey.